Currently, the display of electronic devices, such as smart phone and tablets, is becoming increasingly large. Users usually provide a protective cover to their electronic devices to protect the screen of the electronic devices in use, and the protective cover can also be used to achieve functions of locking and waking up the screen.
In order to achieve the lock screen and wake up functions of the electronic device, the electronic device is usually provided with a Hall sensor, while the protective cover is provided with a magnet, so as to ensure that the Hall sensor is in the magnetic field of the magnet when the protective cover is closed. In order to make sure that the Hall sensor is able to be switched on and off under the action of the magnet, it is necessary that the relative position between the Hall sensor and the magnet meets a high requirement. In some situation, there is a distance between the magnet and the Hall sensor in a transverse direction of the screen, such that when the protective cover is folded, the Hall sensor fails to pass through the magnetic lines of the magnet if the cover moves right or left. Thus, a manner of enhancing the magnetic field intensity of the magnet is usually adopted so as to allow the Hall sensor to pass through by the magnetic lines of the magnet even if the protective cover moves right or left.